Inhaled Insulin

What is the problem and what is known about it so far?
Because people with type 1 diabetes can't make insulin and need to take it, they usually need more than one type of manufactured insulin to control their diabetes. The different types of insulin work at different rates and for different amounts of time. Three commonly used types of insulin are "short-acting," "intermediate-acting," and "long-acting."
Short-acting insulin works much faster than intermediate- or long-acting insulin, and it is used around mealtime. Short-acting insulin should be taken about 30-45 minutes before eating, and it peaks at about 2-3 hours. It can keep working for as long as 6 hours.
Intermediate-acting insulin is insulin mixed with a substance that makes the body absorb the insulin more slowly. It takes longer to start to work, and it stays in your body for a longer time. NPH is a type of intermediate-acting insulin that usually begins to work about 2-4 hours after injected. It peaks 4-10 hours after injection, and it keeps working for 10-16 hours.
Long-acting insulin starts to work in 6-10 hours and can stay in the body for 20 hours or more. It has a peak, but its top speed looks a lot like its normal speed. Like intermediate-acting insulin, it is usually taken in the morning or before bed.
People with type 1 diabetes can often keep their glucose levels under control by taking shots of intermediate-acting or long-acting insulin in the morning or before bed, as well as taking shots of short-acting insulin before meals. However, even though this type of routine has been shown to work for people with type 1 diabetes, many patients often stray from this routine, probably because of the burden of taking so many shots.
Why did the researchers do this particular study?
The researchers wanted to see if there was an easier way for patients with type 1 diabetes to take intermediate- or long-acting insulin in addition to taking short-acting insulin. They looked at whether inhaling short-acting insulin, in addition to taking shots of intermediate-acting insulin, was as good at controlling diabetes as taking shots of both short-acting insulin and intermediate-acting insulin.
Who was studied?
Patients with type 1 diabetes who took part in the Inhaled Insulin Phase III Type 1 Diabetes Study. The patients were between 12 and 65 years of age and had been taking two or more shots of insulin each day for at least 2 months before the study began.
How was the study done?
All of the patients took shots of intermediate-acting NPH insulin twice a day. In addition to those shots, 165 patients took shots of short-acting insulin before meals, and the remaining 163 patients inhaled short-acting insulin before meals. The inhaled insulin was a dry-powder insulin delivered with a device that looks a bit like an asthma inhaler.
During each day of the study, the patients measured their blood glucose levels before each meal, 2 hours after a meal, and before they went to bed. The study lasted for 6 months.
What did the researchers find?
Both groups were able to lower their A1C (a measure of long-term blood glucose control) to similar levels, and almost the same number of patients in each group were able to lower their A1C to the ideal range (less than 7%).
The blood glucose measurements taken 2 hours after a meal were about the same in each group, but the group who took inhaled insulin had lower blood glucose levels at bedtime.
The patients who took the inhaled insulin had hypoglycemia (low blood glucose, also known as an “insulin reaction”) less often, but had severe hypoglycemia (dangerously low blood glucose) more often.
What were the limitations of the study?
The patients were responsible for giving themselves the insulin and taking their own blood glucose measurements. The size of insulin doses may have slightly varied among the patients, and the patients may have taken their measurements at different times. These types of differences could slightly affect the results.
This was a fairly short study, and the researchers are conducting more studies to look at how inhaled insulin affects the long-term health of the lungs.
What are the implications of the study?
For patients with type 1 diabetes who aren't able or don't want to take insulin shots before each meal, inhaling short-acting insulin may be a good alternative to help control their diabetes.